Most countries in Africa south of the Sahara a. became independent during 1800s
b. became colonies during the
c. gained independence between 1950 the 1800s. and 2000.
d. joined in a single union of African 1950s and 1960s. states in 1999

This is a 2017 topographic map of puerto rico in the united states, and i'm sorry that people there have suffered such a disaster. i want to ask, what do the yellow dots and areas represent on this graph? and the blue area and the little blue circle, and the little blue sign that looks like a signal tower, what do they stand for?